Maryland severe storm shows off superb structure

A storm near Thurmont, Md. is viewed from just northwest of Woodsboro, Md. A non-rotating wall cloud which formed rapidly in the minutes prior is seen over the road with a shelf cloud extending to the north. (The storm was heavily outflow dominant at this point and this was taken shortly after the last warning expired on it.) View large. Even though it was a “conditional” threat for severe weather, it’s hard to say the storms on Friday, August 10, lived up to their potential across the area. Part of that reason was the very slow movement of the upper level energy and the cold front associated with it. Also, morning rain and an intensifying front-running system (which later slammed New England) helped to stabilize the air.

There was still sufficient potential to motivate myself and meteorologist Mark Ellinwood to attempt a mid-Atlantic storm chase. We left the D.C. area early afternoon and headed northwest towards a zone where instability was building in the wake of morning storms. It was also a bit closer to more favorable upper-level winds (compared to further east).

A look at reports to NOAA’s SPC in the northeast on August 10, 2012. The storm produced several wind damage reports along its path. We initially staged in Frederick, Md. to grab a late lunch and determine our target. At this point radar was mainly quiet, and concerns were growing that storms would not materialize. The main story was increased midday sunshine, helping to build fuel in the atmosphere for possible storms, but ultimately did not help spawn many.

However, ingredients continued to come together at the eastern end of the higher terrain to the west, so we pushed further northwest, eventually to the west of Hagerstown. At the same time, showers — aided by orographic enhancement — started to blossom into thunderstorms over the West Virginia panhandle, western Maryland and into southern Pennsylvania.

We got first sight of a building storm across the border while to the southwest of Clear Spring, Md., right across the river from WV. Within 45 minutes the storm was in Maryland and a severe thunderstorm warning issued. We headed back east to stay in front of it.

While the storm was predominantly outflow dominant (expelling more cold stable air, than ingesting moist, unstable air), there were some signs of rotation particularly early in its life, and the storm exhibited supercell characteristics off and on.

Developing storms approach Maryland from West Virginia. Photo taken between Hancock and Hagerstown, Md. The strongest of the two storms was just cresting the far hill at left at this point, and this would later become the severe storm we’d track.

A mature severe thunderstorm to the east of Clear Spring, Md. Viewed from north of Williamsport, Md. View large.

Outflow from the severe thunderstorm approaches our location.

The southern end of the severe thunderstorm near Hagerstown, Md., as seen from north of Boonsboro. View large.

After our last look, the storm headed east into an area of limited road options, so we left it for some time to travel by highway. This image from inside the car is on approach to the storm while heading up 15. A shelf cloud can be seen spilling into the little valley in the area.

The storm approaches Thurmont, Md., as seen from south of the town.

Thunderstorm over Thurmont, viewed from near Woodsboro, Md. A wall cloud is noted developing over the road (this was taken moments before the lead shot). View large.

The storm continues east as it slowly weakens. We decide to call it a chase to the east of Woodsboro, but get a final pretty view. View large.

Comments our editors find particularly useful or relevant are displayed in Top Comments, as are comments by users with these badges: . Replies to those posts appear here, as well as posts by staff writers.

To pause and restart automatic updates, click "Live" or "Paused". If paused, you'll be notified of the number of additional comments that have come in.

Comments our editors find particularly useful or relevant are displayed in Top Comments, as are comments by users with these badges: . Replies to those posts appear here, as well as posts by staff writers.